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rocksdb/db/read_callback.h

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include "rocksdb/types.h"
namespace rocksdb {
class ReadCallback {
public:
virtual ~ReadCallback() {}
// Will be called to see if the seq number visible; if not it moves on to
// the next seq number.
virtual bool IsVisible(SequenceNumber seq) = 0;
// This is called to determine the maximum visible sequence number for the
// current transaction for read-your-own-write semantics. This is so that
// for write unprepared, we will not skip keys that are written by the
// current transaction with the seek to snapshot optimization.
//
// For other uses, this returns zero, meaning that the current snapshot
// sequence number is the maximum visible sequence number.
inline virtual SequenceNumber MaxUnpreparedSequenceNumber() { return 0; };
};
} // namespace rocksdb